The Linux Operating System

The Linux operating system is a freely available version of Unix. It consists
of the Linux kernel, together with a very large number of free utility programs,
much of it produced by the Free Software Foundation.

The Linux kernel was written by Linus Torvalds. Version 2.0 is the current
stable kernel. The current patch-level is 2.0.36. There is also a development
kernel, which is currently 2.1.129, and rapidly approaching release as stable
kernel 2.2.